Piston and piston rod assembly



June 22, 1937. L, HAMER 2,084,439

PISTON AND PISTON ROD ASSEMBLY Filed March 10, 1954 2 Sheets-Sheet l L. S. HAMER P h 0 m w m aw \h June 22, 1937.

Patented June 22, 1937 UNITED STATES] PATENT OFFICE amuse rrs'ron AND PISTON non ismm mm! s. min r, Long Beach, Calif.

Application March 10.

. :2 Claim. This invention relates to pistons and piston rods and relates more particularly to a piston and piston rod'assembly. A general object of this invenand to taper the rod receiving opening of the pis-.

ton. In such cases the piston retaining nut urges the piston onto the tapered rod and where the fluid is handled at high pressures the piston becomes more tightly forced or wedged on the rod through "its action-Jon the fluid. In many instances a piston becomes so tightly wedged or forced on the piston rod that it must be broken to free it from the rod. 4 I 1 Another object of the invention is to provide a piston and piston rod assembly formed and provided with means whereby the piston may be 'easily and quickly removed from the rod.

. Another object of the invention-is to provide a piston and piston rod assembly in which the piston is normally firmly and depe'ndably retained on the rodbut may be readily removed from the rod without striking, jarring, heatingor applying external force to the assembly.

. Another object of the invention is to provide a piston and piston rod assembly adapted to be disconnected by fluid under pressure acting between the contacting portions of the assembly.

Afurther object of the invention is to provide an assembly of the character mentioned in which the rod or piston has a port for carrying fluid pressure to a confined space'between the contact- 4() ing parts for freeing the piston from the rod.

A still further object of the invention is to provide a piston and piston rod assembly of the character mentioned that is simple and inexpensive of manufacture.

Other objects and features of the inventionwill be better and more fully understood from the following detailed description of typical forms and applications of the invention, throughout which description reference may be had to the accompanying drawings, in which:

Fig. l is a longitudinal detailed sectional view of one form of the invention illustrating one type of pressure developing means in operative position on the piston rod. Fig. 2 is a longitudinal detailed sectional view of another form of the invention 1984, Serial No. 715,031

showing another type of pressure developing means, and Fig. 3 is an enlarged fragmentary de tailed sectional view of a portion of the pressure developing device illustrated in Fig. 2.

The present invention is adapted to be embodied in piston and piston rod assemblies for use in various classes and forms of mechanisms and in assemblies where the piston involves various types of sealing'means and other features. Throughout the following detailed, disclosures I will describe the invention embodied in typical'forms including a; piston of a general type employed in slush pumps, and the like. It is to be understood that the invention is not to be construed as limited or restricted to the speciflc forms or applications about to be described but is to be taken as including any features or modifications that may fall within the scope of the claims.

The embodiment of the invention illustrated in Fig. 1 includes, generally, a rod H), a piston hub or body II on the rod lll,'a member l2 of resilient material on the body II for slidably sealing with the wall of a cylinder and means IS in the rod III for supplying or conducting fluid pressure for freeing the body II from the rod 1.0.

The piston rod -Ill may resemble, generally, the piston rods employed inthe variouscylinder and piston mechanisms. The main portion ll of the rod l0 may be cylindrical, as illustrated. The portion I! of the rod ID for receiving or carrying the body ll of the piston is longitudinally tapered and of round cross section. The end portion lGof the piston rod has a comparatively long screw thread H for receiving the usual piston retaining nut and lock nut (not shown). The threaded end portion I6 projects axially beyond the end of-the piston.

The hub or body ll of the piston may be a simple integral member and is provided witha'central longitudinal opening l8 for receiving the piston rod ill. The opening I 8 is longitudinally tapered and the body II is normally arranged or set on the rod so that the walls of the opening l8 tightly and evenly bear on the surface of the tapered portion i5 of the rod. The tapered rod portion l5 and the wall of the opening l8 are preierably accurately finished to have close effective cooperation. The hub or body ll of the piston carries the member I! and its construction and shape depend upon the shape and character of the cylinder engaging means embodied in the piston. In the particular case illustrated in the drawings the body H has a radial annular end flange I! provided with a tapered or inclined inner side 20. The opposite end portion 2| of the rod l and having a socket 29 receiving-the The folreduced end portion-2i of the body ll. lower 22 has an inclined inner side 24 for bearing against the end of the member l2. Ports 25 are provided in ,the flange l9 and follower 22 to permit' the fluid pressurein the cylinder to act against the opposite ends of the resilient sealing member l2. The member l2 extends outwardly beyond the flange l9 andfollower 22 to have its sure to a'spaqe between the contacting tapered surfaces ofthe rod l0 and body II to free or disengage t he bbdy H from the rod. In accordance with the form of the invention being,described the means '19 provides or includes a longitudinal opening26 in the piston rod i0.- The opening 29 extends inwardly from the end of the rod and may terminate at a point within the tapered portion l5 of the rod.- The opening 29 may be uniform in diameter and its wall is accurately ground or finished; A threaded socket 21 is provided in the outer end of the opening 20 for normally receiving a plug and for facilitating the connection of a fluid pressure supplying mean's with the rod it as will be hereinafter described.

One or more ports 29 are provided in the rod I. to

connect .the opening 26 with the pressure "space between the rod and piston body I I;

In the particular form of the invention being described the confined pressure space is in the nature of a groove 20 in the surface of the tapered portion l5 of the piston-rod. The groove 29 is preferably annular to surround the rod l9 and is spaced between the opposite ends of the F t n body Ii. In accordance with'the broader aspects of the invention the space or groove, 29 may be of any desired cross sectional configuration. The space or groove 29 is provided to receive fluid pressure for freeing or disconnecting the piston body ii from the rodill. Fluid pressure is passed. to the space or groove 29 from the opening 26 through the ports 29 and upon the pressure reaching a certain value it acts outwardly on the'pi'ston body Ii and inwardly on the. rod I l to suddenl release the piston body I I from the rod.

. Fig. 1 illustrates one form of apparatus described and claimed in my co-pending application referred to above for supplying fluid pressure to the space or groove 299. This pressure developing' means or apparatus includes a tubular body member adapted to be threaded on the projecting end portion ii of the piston rod II. A screw 9| is threaded into the member 99 and carries a plunger 92 which operates in the opening 29 of the piston rod. The outer end of the screw 9| is provided with a suitable polygonal head 99 for engagement by a wrench or turning tool. The inner end ofthe plunger 92 carries a cup leather or plunger cup 94 for slidably sealing withthe wall of the opening 29. A nut 98 is removably keyed on a reduced end part of the plunger to retain the plunger cup 94 in its operative position on the plunger. The screw 9| is adapted to be threaded inwardly in the member 99 to operate the plunger 32 in the opening 29 to develop fluidpressure in the opening and the groove 29 for disconnecting the piston body H from the rod I0.

The groove 29 and the opening 29 are provided with a suitable fluid such as grease. This fluid may be supplied to the groove and opening when the piston is assembled on therod "and maybe retained therein by the, plug threaded; in the socket 21. When it is desired to remove the piston from the rod 19 the lock nut and the piston retaining nut are threaded from the projecting portion i6of the rod. The fluid retaining plug is alsoremoved from the socket 21. The member 30 of the pressure developing apparatus is then threaded'on the rod and the plunger 92 is started in theoperiing -29. The screw 9i is then engaged and turned to operate the plunger ,92 inwardly against the grease or .fluidin the opening 26. This operates to put the fluid in the groove 29 under pressure. When the fluid is put under a sufficiently high pressure the. body ll of the piston is suddenly freed from the piston rod ill. The space or groove 29 is sealed by the wedged or closely contacting surfaces of the piston rod and piston body H and the fluid under high pressure in the groove 29 exerts anexpandingforce.

and the member 99 is. unthreaded from the rod.

The piston may then be easily removed from the rod.-

Fig. 2 of the drawings illustrates an embodiment of the invention in which themeans, II for supplying or conducting fluid pressure tothe space between the piston body I]! and the piston rod III- is provided in the piston body II. The piston and piston rod illustrated in Fig. Zare substantially identical with the piston and rod described above, it being understood that the in; vention as disclosed in- Fig. 2 may be embodied in pistons varying considerably in character. The piston rod III has a longitudinally tapered'portion Is and a threaded end portion IO for the reception of the piston retaining nut and look not (not shown). A resilient annular member l2 surrounds the piston body Il and is provided for slidably sealing with the wall of the cylinder. An end plate or follower 22- clamps the sealing body Jl'. The piston body II has a central longitudinal opening II which is longitudinally tapered to tightly receive the tapered'portion ll of the piston rod.

The means i9 is provided to conduct fluid pressure to a space between the contacting portions of the piston rod and piston body for the purpose 'member i2 against a flange l9! on the piston of freeing or disconnecting the piston body from the rod. The means l9 includes a port 49 in the piston body ii extending to the space between The groove II is preferably continuous or suitable shape. In the particular case illustrated the groove 4| is substantially triangular in crosssectional configuration having an outer wall pitched in the opposite direction to the wall of the opening I8 and a substantially normal end wall. The port 40 extends from the groove 4| to the reduced outer end of the body ll.

.Means is provided at the outer end of the port 40 for facilitating the connection of a pressure developing or supplying means with the piston body. A screw-threaded socket 42 is provided in the outer end of the port 40. An opening 43 is provided in the follower 22 to register with the socket 42. The outer portion of the opening 43 may be threaded for normally receiving a plug (not shown). The socket 42 may normally carry a plug for closing the outer end of the port 40 to retain a suitable fluid in the port and groove 4|. When the plugs are removed from the socket 42 and the opening 43 fluid pressure may be supplied to the port 40 and groove 4| for the purpose of freeing or disconnecting the piston body II"- from the rod I.

Figs. 2 and 3 of the drawings illustrate another form of pressure supplying or developing means for use in connection with the piston and piston rod assembly of the invention. The pressure supplying or developing means disclosed in Figs. 2 and 3 is fully described and claimed in my copending application referred to above. The device or apparatus for supplying fluid pressure to the port 40 includes a body member illl which may be identical with the member 30 and a screw 3| threaded into the member 30. The screw 3| projects from the end of the member 30 and carries a polygonal head 33". A tubular member or cylinder 45 is screw threaded into the inner end of the member 3|! and its opening 46 receives adapter 55. The adapter 55 is adapted to be passed through the opening 43 and its end is adapted to be threaded into the socket 42 of the piston body II.

To remove the piston from the rod lo the usual nut and lock nut are removed from the threaded end l6 of the rod. The plugs (not.

shown) are removed from the socket 42 and the opening 43 and the adapter 55 is threaded into the socket. The groove 4| and the port 40 are preferably supplied with grease or the like when the piston is assembled on the 'rd'deand a similar fluid is provided in the cylinder opening 46. Inward movement of the plunger 32' places the fluid in the space or groove 4| under a high pressure. When the pressure in the space 4| becomes sufliciently great the piston body H is suddenly sprung and shifted free of the piston rod l0 so that the piston may be easily removed from the rod. It will be apparent how the fluid under high pressure in the space or groove 4 acts outwardly against the piston body and inwardly against the rod ID to release the piston body from the rod. The pressure developing device or apparatus illustrated in Figs. 2 and 3 of the drawings is suitable for use in removing the piston body II from the rod Ill as its pin 5| is adapted to be threaded into the opening 21 so that fluid pressure may be supplied from the opening 45 to the opening 26 and groove 29.

The present invention provides piston and piston rod assemblies that are adapted to be easily and quickly disconnected by the operation of internal fluid pressures. The means for supplying or delivering the fluid pressure to the space between the contacting parts of the piston body and rod does not greatly complicate the construction and may be embodied in piston and piston rod assemblies varying considerably in character. The invention is suited for embodiment in piston and piston rod assemblies employed in mechanisms handling fluid at high pressures, because it provides a means for easily and readily removing the pistons from the rods in cases where the pistons have become tightly wedged or set on the rods.

Having described only typical preferred forms and applications of my invention, I do not wish to be limited or restricted to the speciflc forms and applications herein set forth, but wish to reserve to myself any modifications or variations that may appear to those skilled in the art or fall within the scope of the following claims.

Having described my invention, I claim:

1. In combination, two parts, one a rodhaving a tapered portion, the other a piston having a tapered opening receiving the tapered portion of the rod, there being an annular space between the contacting parts surrounding the rod, one of the parts having an opening extending to said space to conduct fluid pressure thereto, a member removably threaded on said part, and a plunger threaded in the member and operable in the opening to create pressure in the space to disconnect the parts.

2. In combination, two parts, one a rod having a tapered' portion, the other a piston having a tapered opening receiving the tapered portion of the rod, there being an annular space between the contacting parts surrounding the rod, one of the parts having an opening extending to said space to conduct fluid pressure thereto, a member removably threaded on the rod, and a plunger threaded through the member to operate in the opening and create pressure in the space to disconnect the parts. v

LELAND S. HAMER. 

